STS-37 Mission Watch (12/03/1991) STS-37 Gamma Ray Observatory The second of NASA's Great Observatories, the Gamma Ray Observatory or GRO, will be deployed into space by the crew of the Space Shuttle Atlantis on the STS-37 mission this spring. The first of these observatories was the Hubble Space Telescope that was launched in 1990. At 15,655 kilograms, the GRO will be the heaviest payload ever deployed by the Shuttle's remote manipulator system arm (RMS). On flight day three, the GRO will be lifted out of Atlantis's payload bay with the orbiter's remote manipulator system arm. Following the unfolding of the spacecraft's solar arrays and high-gain antenna and the charging of its batteries, the GRO will be released. Atlantis will then move slowly away by firing its reaction control system engines. In addition to deploying the spacecraft, the STS-37 crew, during its five-day mission, will be conducting a variety of middeck scientific experiments and the first extravehicular activity (EVA) in five and a half years. Gamma Ray Observatory Astronomers around the world are eager for the launch of the GRO because the spacecraft will help them to fill in missing pieces in our view of the universe about us. Outer space is filled with electromagnetic radiation that tells the story of the birth and death of stars and galaxies. Only a small portion of that radiation is visible to our eyes. The rest can be detected only with special instruments. Gamma rays are one form of invisible radiation. In a chart of the electromagnetic spectrum, gamma rays fall at the far right end after visible light, ultraviolet light, and X rays. Gamma rays have very short wavelengths and are extremely energetic, but most of them do not penetrate Earth's atmosphere. The only way for astronomers to view these waves is to send instruments into space. The GRO is a complex spacecraft fitted with four different gamma ray detectors, each of which concentrates on different but overlapping energy ranges. The instruments are the largest of their kind that have ever flown in space. This is important because gamma rays can only be detected when they interact with matter. The bigger the masses of the detectors, the greater the number of gamma rays they can detect. The process for gamma ray detection is similar to the way fluorescent paints convert ultraviolet light to visible light. When gamma rays interact with crystals, liquids, and other materials, they produce flashes of light that are recorded by electronic sensors. Astronomers can determine how energetic a particular ray is from the intensity of the flash. The brighter the flash of light from the interaction, the higher the energy of the ray. The four different kinds of gamma ray detectors on the GRO are the Burst and Transient Source Experiment (BATSE), Oriented Scintillation Spectrometer Experiment (OSSE), Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). The BATSE experiment consists of eight detectors placed on the corners of the spacecraft. The other experiments consist of single devices. Astronomers will compare the intensities and directions of gamma ray interactions with the GRO's detectors to learn about the most powerful celestial bodies and events in the universe. The GRO will help astronomers address fundamental questions about the process of energy transfer in the universe and provide a new understanding of the processes at work in supernovas, neutron stars, pulsars, and quasars. EVA Extravehicular activity, or spacewalking, has been an essential element of many NASA manned space missions. EVA has been used for exploration of the Moon's surface, repair of the Skylab space station, and satellite retrieval and repair. EVAs are planned for the assembly and operation of Space Station Freedom. In preparation for future EVAs, two of the STS-37 crew members will don Shuttle space suits and exit Atlantis's airlock into the payload bay on flight day four. They will be experimenting with new apparatus and techniques for moving equipment and themselves about and for doing work in space. The EDFE (EVA Development Flight Experiment) consists of three elements: (1) flight-testing various methods of getting around large space structures; (2) learning how much force an EVA astronaut can exert to rotate a bolt or move a piece of equipment; and (3) finding the most efficient ways to use the Shuttle's RMS to aid an EVA astronaut in moving to work sites and installing equipment. Getting around large space structures ranges from using simple methods like pulling hand-over-hand along a rope to complex methods involving mechanical or electrical devices. Once in the payload bay, the EVA crew will assemble a 15-meter-long track. Various carts will be tested on the track. One cart operates somewhat like a railroad hand-car and transforms astronaut movements of a push bar to mechanical thrust. A second cart is propelled by an electric motor that gets electricity from a generator powered by hand cranks. Additional translation experiments will involve using a rope reel device and hand rails for translation. Secondary Experiments Built into the STS-37 schedule around GRO deployment and extravehicular activities are a variety of materials and systems experiments. The Protein Crystal Growth II (PCG II) experiment is a continuation of an earlier experiment flown on the Space Shuttle. Researchers are hoping the microgravity environment of the Space Shuttle will permit the experiment to grow large protein crystals with few, if any, of the distortions that occur in the one-gravity environment on Earth. When returned to Earth, the atomic structures of the crystals will be examined to help scientists develop more effective medicines with fewer side effects. The Bioserve Instrumentation Technology Associates Material Dispersion Apparatus (BIMDA) is a commercial experiment that will demonstrate technology for biomedical and fluid science experiments. BIMDA has four material dispersion laboratories that can automatically mix as many as 182 samples in 35 separate biomedical and chemical experiments developed by 22 researchers. The BIMDA apparatus fits in the space of a single locker on Atlantis's middeck. Because of its compact size and potential for automatic operation, the developers of the apparatus believe it will make microgravity research more affordable to scientists and small companies. Other experiments include the Space Station Heat Pipe Advanced Radiator Element II (SHARE II) middeck experiment and the Radiation Monitoring Equipment III (RME III). The SHARE II middeck experiment will investigate heat pipe technology for transferring heat from one location to another. A heat pipe is a sealed tube with a fluid inside. The pipe absorbs heat on one end and transports it via the fluid to the other end, where it is radiated. Heat pipes are extremely efficient heat-transfer devices and the experiment seeks to develop future space station versions of the pipes that will be equally efficient in the microgravity environment in space. The RME III experiment is a continuation of earlier Shuttle experiments aimed at a better understanding of the nature of radiation environment in Earth orbit. The Air Force Maui Optical Site Calibration Test (AMOS) does not involve any experimental apparatus on Atlantis. As Atlantis passes within optical range of the Air Force Maui site, Atlantis will fire some of its reaction control system engines to initiate brief rolling motions. Instruments at the optical site will observe Atlantis and compare its appearance from the ground with its known orientations in space. The Shuttle Amateur Radio Experiment II (SAREX II) is being flown for the American Radio Relay League, the Amateur Satellite Corporation, and NASA Headquarters' Educational Affairs Division. In preparation for the experiment, all five STS-37 crew members earned amateur radio licenses. When time permits, they will use a VHF radio transmitter and receiver to contact ham radio operators around the world with radio. During the flight, the crew will make a special effort to use SAREX to make contact with students in several schools across the United States. STS-37 Quick Facts Crew: Steven R. Nagel - Col., USN - Commander Kenneth D. Cameron - Lt. Col., USMC - Pilot Jerry L. Ross - Lt. Col., USAF - Mission Specialist Jay Apt - Ph.D. - Mission Specialist Linda M. Godwin - Ph.D. - Mission Specialist Vehicle: OV-104 Atlantis Mission duration: 5 days Orbital inclination: 28 degrees Orbital altitude: 450 km Primary payload: GRO - Gamma Ray Observatory Secondary payloads EDFE- EVA Development Flight Experiment and experiments: PCG II - Protein Crystal Growth II RME III - Radiation Monitoring Equipment III AMOS - Air Force Maui Optical Site Calibration Test SAREX II - Shuttle Amateur Radio Experiment II BIMDA - Bioserve Instrumentation Technology Associates Materials Dispersion Apparatus SHARE II Middeck - Space Station Heat Pipe Advanced Radiator Element II Classroom Activities and Questions 1. The entire progress of the mission from launch to landing can be observed on television if your school has a satellite dish. Direct the dish to the SATCOM F2R satellite at 72 degrees west longitude. Tune into NASA Select, transponder 13, 3960 megahertz. If your school does not have a satellite dish, but does have a cable television hookup, call your local cable operators and request they receive NASA Select and distribute it on one of their channels or tape it for your use. Check local news services for updates on Atlantis's liftoff or call the NASA Kennedy Space Center at 407-867-2525 for a recorded message. 2. Contact the American Radio Relay League for the name of a local amateur radio operator who might be willing to provide a SAREX demonstration for your classroom. The league is coordinating a number of educational activities related to the experiment. American Radio Relay League 225 Main Street Newington, CT 06111 3. Examine an electromagnetic spectrum diagram for the position of gamma rays. Diagrams are found in many astronomy and physics textbooks and encyclopedias. Research how gamma rays are produced and detected and their significance to astronomy. 4. Use a skateboard for classroom tests of EVA translation. Have a student stand on the skateboard and try to move across the room by pulling on a rope tied to opposite ends. Ask the students to invent mechanical and electrical devices that would aid an astronaut in moving about a space station. 5. Why are scientists interested in growing perfect crystals in space? 6. Check astronomy magazines for articles about NASA's Great Observatories, including the Hubble Space Telescope, the Gamma Ray Observatory, the Advanced X-Ray Astrophysics Facility (planned), and the Space Infrared Telescope Facility (planned). References NASA (1989), "Amateur Radio in Space," NASA Educational Briefs for the classroom, EB 89-1, National Aeronautics and Space Administration, Washington, D.C.. NASA, "Gamma-Ray Observatory: Exploring the Mysteries of Time," NASA Goddard Space Flight Center, Greenbelt, MD. NASA, The Gamma-Ray Observatory, NP-124, National Aeronautics and Space Administration, Washington, D.C. Smith, D.H. (May 1990), "Seeking the Origins of Cosmic Rays," Sky and Telescope, 479-484. Smith, B.A. (May 5, 1990), "Gamma-Ray Observatory to Study Celestial Forces that Shaped the Universe," Aviation Week and Space Technology, 70-73. White, R. (1991), "SAREX: Sharing the Exploration of Our World and Beyond," QST, 75:2,44-46.